Method and system for providing credit for participation in an ad hoc network

ABSTRACT

A method and system for providing credit for participation in an ad hoc wireless communication network is useful for improving network efficiency. The method includes receiving at a first network node a first data packet transmitted from a second network node (step  305 ). The first data packet includes payload data and credit claim data. The first node then determines that the credit claim data should be forwarded to a credit accounting authority (step  310 ), so a second data packet is then transmitted from the first node to the credit accounting authority (step  315 ). The second data packet includes some of the credit claim data. The first node then transmits a third data packet to a third network node, where the third data packet includes the payload data (step  320 ).

FIELD OF THE INVENTION

The present invention relates generally to data routing in ad hocwireless communications networks, and in particular to providingincentives to network nodes to participate as intermediate nodes.

BACKGROUND

Many wireless communications systems require a rapid deployment ofindependent mobile users as well as reliable communications between usernodes. Mobile Ad Hoc Networks (MANETs) are based on self-configuringautonomous collections of mobile users who communicate with each otherover wireless links having limited bandwidths. MANETs are usuallytemporary packet radio networks which do not involve significant, ifany, supporting infrastructure. Rather than employing fixed basestations, each user node in a MANET can operate as a router for otheruser nodes, thus enabling expanded network coverage that can be set upquickly, at low cost, and which is highly fault tolerant.

MANETs provide critical communication services in various environmentsinvolving, for example, emergency services supporting police and firepersonnel, military applications, industrial facilities and constructionsites. Routing communications between two nodes in a static networkgenerally involves simply determining the shortest route between the twonodes. However, in a MANET, the determination of an optimalcommunication route may involve additional factors. For example,propagation path losses, interference between users, and channel fadingmay require the use of an indirect route between two nodes in order toprovide an acceptable Quality of Service (QoS) to the network users.

Because MANETs generally do not comprise significant supportinginfrastructure, such as fixed base stations, but rely on user nodes toact as relay or intermediate nodes, participation in a MANET by a highnumber of users is often critical to network functionality. For example,if a MANET covers a significant area that is wider than the transmissionrange of any single user node, a transmission across the full width ofthe MANET will require relaying the transmission through at least oneintermediate user node. Unless an adequate number of such intermediate,or “multi-hop”, user nodes participate in the network, and enabletransmissions addressed to other nodes to be routed through theintermediate user nodes, then the network breaks down and at least sometransmissions may not be completed. Conversely, as more user nodesparticipate in a MANET, the average distance between nodes decreases,and reliability and link quality increases.

BRIEF DESCRIPTION OF THE FIGURES

The accompanying figures, where like reference numerals refer toidentical or functionally similar elements throughout the separate viewsand which together with the detailed description below are incorporatedin and form part of the specification, serve to further illustratevarious embodiments and to explain various principles and advantages,all in accordance with the present invention.

FIG. 1 is a schematic diagram of a communication network comprising aplurality of communication nodes, according to an embodiment of thepresent invention.

FIG. 2 is a schematic diagram illustrating features of specific datapackets that are used to relay a data payload between nodes in an ad hocwireless communication network, according to an embodiment of thepresent invention.

FIG. 3 is a general flow diagram illustrating a method for providingcredit for participation in an ad hoc wireless communication network,according to an embodiment of the present invention.

Skilled artisans will appreciate that elements in the figures areillustrated for simplicity and clarity and have not necessarily beendrawn to scale. For example, the dimensions of some of the elements inthe figures may be exaggerated relative to other elements to help toimprove understanding of embodiments of the present invention.

DETAILED DESCRIPTION

Before describing in detail embodiments that are in accordance with thepresent invention, it should be observed that the embodiments resideprimarily in combinations of method steps and apparatus componentsrelated to providing credit for participation in an ad hoc network.Accordingly, the apparatus components and method steps have beenrepresented, where appropriate, by conventional symbols in the drawings,showing only those specific details that are pertinent to understandingthe embodiments of the present invention so as not to obscure thedisclosure with details that will be readily apparent to those ofordinary skill in the art having the benefit of the description herein.

In this document, relational terms such as first and second, top andbottom, and the like may be used solely to distinguish one entity oraction from another entity or action without necessarily requiring orimplying any actual such relationship or order between such entities oractions. The terms “comprises,” “comprising,” or any other variationthereof, are intended to cover a non-exclusive inclusion, such that aprocess, method, article, or apparatus that comprises a list of elementsdoes not include only those elements but may include other elements notexpressly listed or inherent to such process, method, article, orapparatus. An element preceded by “comprises a . . . ” does not, withoutmore constraints, preclude the existence of additional identicalelements in the process, method, article, or apparatus that comprisesthe element.

It will be appreciated that embodiments of the invention describedherein may be comprised of one or more conventional processors andunique stored program instructions that control the one or moreprocessors to implement, in conjunction with certain non-processorcircuits, some, most, or all of the functions of providing credit forparticipation in an ad hoc network described herein. The non-processorcircuits may include, but are not limited to, a radio receiver, a radiotransmitter, signal drivers, clock circuits, power source circuits, anduser input devices. As such, these functions may be interpreted as stepsof a method to provide credit for participation in an ad hoc network.Alternatively, some or all functions could be implemented by a statemachine that has no stored program instructions, or in one or moreapplication specific integrated circuits (ASICs), in which each functionor some combinations of certain of the functions are implemented ascustom logic. Of course, a combination of the two approaches could beused. Thus, methods and means for these functions have been describedherein. Further, it is expected that one of ordinary skill,notwithstanding possibly significant effort and many design choicesmotivated by, for example, available time, current technology, andeconomic considerations, when guided by the concepts and principlesdisclosed herein, will be readily capable of generating such softwareinstructions and programs and ICs with minimal experimentation.

Referring to FIG. 1, a schematic diagram of a communication network 100comprising a plurality of communication nodes 105-n, according to anembodiment of the present invention is illustrated. The network 100 maybe, for example, a wireless Mobile Ad Hoc Network (MANET), and the nodes105-n may be associated with devices such as mobile telephones orhandheld radios. Also, a base station 110 may form part of the network100 and function as both a network node and as a wireless local areanetwork (WLAN) access point (AP) that provides a gateway to otherwireline networks. Further, a AAA (authentication, authorization,accounting) server 115 may manage AAA procedures associated with thenetwork 100. As described in more detail below, data are routed throughthe network 100 based on various network topology factors including, forexample, node position, node transmitting power, node battery power, anda willingness of a particular node 105-n to act as an intermediate node105-n for relaying messages between other nodes 105-n in the network100.

Maintaining a high Quality of Service (QoS) for users of the network100, and for users of ad hoc networks generally, requires adherence tovarious principles such as minimizing required transmission power,maximizing network range, minimizing radio frequency (RF) interference,and minimizing unnecessary or redundant transmissions between networknodes 105-n. Required transmission power can be decreased, and networkrange can be simultaneously increased, by increasing a number of nodes105-n that are willing to act as intermediate nodes 105-n. For example,as illustrated in FIG. 1, consider that node 105-1 seeks to transmit amessage to node 105-6. One possible multi-hop path for such a message isfrom node 105-1, then to node 105-2, then to node 105-3, then to node105-4, then to the base station 110, then to node 105-5, and finally tothe destination node 105-6. Node 105-6 then can respond by transmittinga response message back to node 105-1 using the same path in reverseorder. Such multi-hop capabilities enable the range of the network 100to be expanded, limited only by the number and position of intermediatenodes 105-n in the network. Also, the close proximity of the nodes 105-nenable each intermediate node 105-n to forward a message to another node105-n using a lower transmission power than would be otherwisenecessary.

The principles of minimizing radio frequency (RF) interference, andminimizing unnecessary or redundant transmissions between network nodes105-n also complement each other. Reducing a total number oftransmissions in the network 100 directly results in less RFinterference, and also conserves battery power at the individual nodes105-n.

In accordance with some embodiments of the present invention, onefunction of the AAA server 115 is to provide incentives for the nodes105-n to act as intermediate nodes 105-n. That can be accomplished byrecording at the AAA server 115 a credit for every time a node 105-nrelays a message in the network 100 between two other nodes 105-n.According to the prior art, it has been proposed that a AAA serverrecord credits to intermediate network nodes by receiving a transmissionfrom each intermediate node every time a data packet is relayed betweennetwork nodes. However, such transmissions between network nodes and aAAA server can significantly increase total network traffic, which canlead to increased congestion, a need for higher transmission power, anda reduced overall QoS for network users.

Referring to FIG. 2, a schematic diagram illustrating features ofspecific data packets 205-n that are used to relay a data payload fromnode 105-1 to node 105-6 in the network 100, according to an embodimentof the present invention is illustrated. Although only components of thedata packets 205-n that assist in describing embodiments of the presentinvention are illustrated, various other components will be understoodby those skilled in the art to be included in the data packets 205-n. Afirst data packet 205-1 is transmitted from node 105-1 to node 105-2.The packet 205-1 comprises a header component 210 and a payloadcomponent 215. The header component 210 identifies the destination node105-6, and may also include other data such as path routing data. Thepayload component 215 can include any type of payload data, such asvoice data, signaling data, or other message data that the node 105-1seeks to send to the node 105-6. The node 105-2 receives the packet205-1 and reads the header component 210 and determines that the payloadcomponent 215 requires relaying to another node 105-n. The node 105-2therefore constructs a second packet 205-2 for transmission to theintermediate node 105-3. The second packet 205-2 also comprises a headercomponent 210 and a payload component 215.

In accordance with the present invention, the second packet 205-2further comprises a credit claim component 220-2. The credit claimcomponent 220-2 includes credit claim data that enable the node 105-2 toobtain credit for acting as an intermediate node 105-2 and relaying thepayload component 215 between node 105-1 and node 105-3. For example,according to one embodiment of the present invention, the credit claimcomponent 220-2 comprises an identification of the node 105-2, such as amedia access control (MAC) address that uniquely identifies the node105-2. The credit claim component 220-2 can also include, for example,verification credentials that prove that the node 105-2 acted as anintermediate node 105-2 for forwarding the payload component 215.

Instead of transmitting the credit claim component 220-2 associated withthe node 105-2 directly from the node 105-2 to the AAA server 115, thecredit claim component 220-2 is forwarded with the packet 205-2 to thenode 105-3. This process reduces the total number of messagestransmitted in the network 100, thus improving network efficiency andincreasing network QoS.

The node 105-3 receives the packet 205-2 and reads the header component210 and determines that the payload component 215 requires relaying toanother node 105-n. The node 105-3 therefore constructs a third packet205-3 for transmission to the intermediate node 105-4. The third packet205-3 also comprises a header component 210 and a payload component 215that forwards the original payload data sent from node 105-1. The creditclaim data from the credit claim component 220-2 associated with node105-2 is also forwarded in the packet 205-3. Further, a second creditclaim component 220-3 associated with the node 105-3 is also included inthe packet 205-3. The credit claim component 220-3 associated with thenode 105-3 includes credit claim data that enable the node 105-3 toobtain credit for acting as an intermediate node 105-3 and relaying thepayload component 215 between node 105-2 and node 105-4.

Multiple credit claim components 220-n can continue to be added to datapackets 205-n as a payload component 215 is forwarded through thenetwork 100. However, as will be understood by those skilled in the art,if the number of hops required to route a payload component 215 throughthe network 100 exceeds a particular threshold, then the networkefficiency gain achieved by eliminating communications betweenintermediate nodes 105-n and the AAA server 115, is outweighed by thenetwork efficiency loss caused by the additional credit claim data thatare required to be transmitted in each intermediate data packet 205-n.That is because the multiple credit claim components 220-n in eachintermediate data packet 205-n add up to a significant proportion of thetotal size of each packet 205-n.

According to an embodiment of the present invention, after the node105-4 receives the third data packet 205-3, the node 105-4 may determinethat adding three credit claim components 220-2, 220-3, 220-4 (one foreach of the intermediate nodes 105-2, 105-3, and 105-4) to a fourthintermediate data packet 205-4 would reduce overall network efficiency.Therefore, the node 105-4 compiles the credit claim data from each ofthe credit claim components 220-2, 220-3 in the packet 205-3 andtransmits a credit accounting data packet to a credit accountingauthority. For example, the credit accounting authority can be the AAAserver 115 or another node 105-n that manages credit claim data. Thecredit accounting data packet is any type of packet that transmitscredit claim data to the credit accounting authority. The creditaccounting data packet can include each of the credit claim components220-2, 220-3 from packet 205-3, or alternatively can include anaggregate summary of the credit claim data from each of the credit claimcomponents 220-2, 220-3 from packet 205-3. After receiving the creditaccounting data packet, the credit accounting authority ensures thateach intermediate node 105-2 and intermediate node 105-3 are properlyvalidated and receive appropriate credit for participating in thenetwork 100.

The node 105-4 then constructs a fourth data packet 205-4 fortransmission to the base station 110. The fourth packet 205-4 alsocomprises a header component 210 and a payload component 215 thatforwards the original payload data sent from node 105-1. However,because the node 105-4 transmits the credit accounting data packet tothe credit accounting authority (either before or after transmission ofthe fourth data packet 205-4), there is no need to include credit claimcomponents 220-2, 220-3 concerning the earlier intermediate node 105-2and intermediate node 105-3 in the fourth data packet 205-4. Therefore,the data packet 205-4 includes only a single credit claim component220-4 associated with the node 105-4, and which includes informationthat enables the node 105-4 to obtain credit for acting as anintermediate node 105-4 and relaying the payload component 215 betweennode 105-3 and the base station 110. Those skilled in the art willappreciate that the base station 110 is described here as only analternative example of a network node through which the payloadcomponent 215 is routed, and various other embodiments of the inventiondo not include use of a base station 110.

The process described above then continues until the payload component215 is delivered to the destination node 105-6. Finally, the destinationnode 105-6 transmits another credit accounting data packet to the creditaccounting authority, so as to provide credit to any intermediate nodes105-n that relayed the payload component 215 since transmission of theprevious credit accounting data packet.

According to an alternative embodiment of the present invention, anintermediate node 105-n can also perform some of the functions of theAAA server 115. For example, according to a specified hierarchy, someintermediate nodes 105-n or the base station 110 can be designated ascharging collection endpoints. Such intermediate nodes 105-n or the basestation 110 will validate charging credentials included in credit claimdata, and then delete previous intermediate node identifications fromthe credit claim data. An aggregated summary of the credit claim datathen can be stored at the designated intermediate nodes 105-n until itis collected by a credit accounting authority.

It is generally desirable that credit claim data cannot be maliciouslymodified or inappropriately fabricated, so that nodes 105-n cannotobtain credit for network participation where such credit has not beenearned. According to still another embodiment of the present invention,such malicious modifications or inappropriate fabrications of creditclaim data can be deterred using data encryption techniques. Forexample, the credit claim component 220-2 can include an authenticationdigest, which is generated using an encryption algorithm, based onparticular credit claim data included in the credit claim component220-2. The authentication digest can be generated using a key that isshared between the node 105-2 and the AAA server 115. Subsequentintermediate nodes such as node 105-3 and node 105-4 then are deterredfrom maliciously modifying the credit claim data in the credit claimcomponent 220-2. That is because if credit claim data on which theauthentication digest is based are modified, such modification will bedetected at the AAA server 115 when the received credit claim component220-2 is compared with the digest. Maliciously modified credit claimdata then can be discarded by the AAA server 115. In addition, a digestgenerated by node 105-2 can be required as a field that is protected bya digest generated by node 105-3. In the embodiment illustrated in FIG.2, that deters node 105-3 from deleting the credit claim component 220-2from the packet 205-3.

Referring to FIG. 3, a general flow diagram illustrates a method 300 forproviding credit for participation in an ad hoc wireless communicationnetwork, according to an embodiment of the present invention. At step305, a first data packet is received at a first network node from asecond network node, and the first data packet includes both payloaddata and credit claim data. For example, referring to the descriptionabove, the node 105-4 receives the packet 205-3 from the node 105-3. Thefirst network node is thus acting as an intermediate node for relayingdata. At step 310, it is determined whether credit claim data includedin the first data packet should be forwarded from the first network nodeto a credit accounting authority. If so, then at step 315 at least someof the credit claim data are transmitted from the first network node ina second data packet, such as the credit claim accounting data packetdescribed above, to a credit accounting authority, such as the AAAserver 115. According to some embodiments, only some of the credit claimdata needs to be forwarded, because it is sometimes possible to compressthe credit claim data into an aggregate summary. At step 320, a thirddata packet is then transmitted from the first network node to a thirdnetwork node.

If at step 310 it is determined that the credit claim data do not needto be currently forwarded to a credit accounting authority, then at step325 the credit claim data are added to data from the first data packetand transmitted. For example, in the network 100 the data packet 205-4is transmitted from the node 105-4 to the base station 110. Step 325effectively defers the forwarding of the credit claim data to a creditaccounting authority. Concerning the first network node, the method 300then cycles back to step 305 where the first network node may receiveanother data packet and again perform as an intermediate node.

Those skilled in the art will recognize that the present invention canbe embodied in a wireless electronic device, such as a device associatedwith a network node 105-n or the base station 110. The device can be,for example, a mobile phone, handheld radio device, personal digitalassistant (PDA), notebook computer, base transceiver station (BTS), ornetwork router. The device can include a standard microprocessor orapplication specific integrated circuit (ASIC) operatively connected toa computer readable medium such as a random access memory (e.g., staticrandom access memory (SRAM)), read only memory (e.g., programmable readonly memory (PROM), or erasable programmable read only memory (EPROM)),or hybrid memory (e.g., FLASH) as is well known in the art. The mediumthen comprises computer readable program code components that, whenprocessed by the microprocessor, are configured to execute the abovedescribed steps of the method 300.

Advantages of embodiments of the present invention thus include moreefficient accounting of credits for intermediate node participation inad hoc wireless communication networks. Rather than requiring a separatetransmission signal for credit claim data from each intermediate node ina network, credit claim data can be accumulated from a plurality ofmulti-hop intermediate nodes. The accumulated credit claim data are thentransmitted to a credit accounting authority only when necessary.Further, accumulated credit claim data can be compressed into anaggregated summary before being transmitted to a credit accountingauthority. That can improve network efficiency by reducing a totalnumber of data packets that are transmitted in a network, and also byreducing an amount of overhead data bytes included in transmittedpackets. Accurate accounting of credits for intermediate node networkparticipation provides an incentive for additional intermediate nodenetwork participation. That results in a more efficient network, lessnetwork congestion and improved QoS for network users.

In the foregoing specification, specific embodiments of the presentinvention have been described. However, one of ordinary skill in the artappreciates that various modifications and changes can be made withoutdeparting from the scope of the present invention as set forth in theclaims below. Accordingly, the specification and figures are to beregarded in an illustrative rather than a restrictive sense, and allsuch modifications are intended to be included within the scope of thepresent invention. The benefits, advantages, solutions to problems, andany element(s) that may cause any benefit, advantage, or solution tooccur or become more pronounced are not to be construed as a critical,required, or essential features or elements of any or all the claims.The invention is defined solely by the appended claims including anyamendments made during the pendency of this application and allequivalents of those claims as issued.

1. A method for providing credit for participation in an ad hoc wirelesscommunication network, the method comprising: receiving at a firstnetwork node a first data packet transmitted from a second network node,the first data packet including payload data and credit claim data;determining at the first network node that the credit claim data shouldbe forwarded to a credit accounting authority; transmitting, from thefirst network node, a second data packet to the credit accountingauthority, where the second data packet includes some of the creditclaim data; and transmitting, from the first network node, a third datapacket to a third network node, where the third data packet includes thepayload data.
 2. The method of claim 1, wherein determining at the firstnetwork node that the credit claim data should be forwarded to thecredit accounting authority is based on a total size of the credit claimdata.
 3. The method of claim 1, wherein the second data packet thatincludes some of the credit claim data comprises an aggregate summary ofthe credit claim data.
 4. The method of claim 1, wherein determining atthe first network node that the credit claim data should be forwarded tothe credit accounting authority is based on a status of the firstnetwork node.
 5. The method of claim 1, wherein the credit claim datacomprise an authentication digest that is based on some of the creditclaim data.
 6. The method of claim 1, wherein the credit accountingauthority is a AAA (Authentication, Authorization, Accounting) serverassociated with the network.
 7. The method of claim 1, wherein the thirddata packet comprises additional credit claim data for providing creditto the first network node.
 8. The method of claim 7, wherein theadditional credit claim data comprises an identification of the firstnetwork node and verification credentials of the first network node. 9.The method of claim 1, wherein the first, second, and third networknodes are each an intermediate node used for transmission of the payloaddata from a source node to a destination node in the network.
 10. Asystem for providing credit for participation in an ad hoc wirelesscommunication network, comprising: computer readable program codecomponents configured to receive at a first network node a first datapacket transmitted from a second network node, the first data packetincluding payload data and credit claim data; computer readable programcode components configured to determine at the first network node thatthe credit claim data should be forwarded to a credit accountingauthority; computer readable program code components configured totransmit, from the first network node, a second data packet to thecredit accounting authority, where the second data packet includes someof the credit claim data; and computer readable program code componentsconfigured to transmit, from the first network node, a third data packetto a third network node, where the third data packet includes thepayload data.
 11. The system of claim 10, wherein determining at thefirst network node that the credit claim data should be forwarded to thecredit accounting authority is based on a total size of the credit claimdata.
 12. The system of claim 10, wherein the second data packet thatincludes some of the credit claim data comprises an aggregate summary ofthe credit claim data.
 13. The system of claim 10, wherein determiningat the first network node that the credit claim data should be forwardedto the credit accounting authority is based on a status of the firstnetwork node.
 14. The system of claim 10, wherein the credit claim datacomprise an authentication digest that is based on some of the creditclaim data.
 15. The system of claim 10, wherein the credit accountingauthority is a AAA (Authentication, Authorization, Accounting) serverassociated with the network.
 16. The system of claim 10, wherein thethird data packet comprises additional credit claim data for providingcredit to the first network node.
 17. The system of claim 16, whereinthe additional credit claim data comprises an identification of thefirst network node and verification credentials of the first networknode.
 18. The system of claim 10, wherein the first, second, and thirdnetwork nodes are each an intermediate node used for transmission of thepayload data from a source node to a destination node in the network.19. A system for providing credit for participation in an ad hocwireless communication network, the system comprising: means forreceiving at a first network node a first data packet transmitted from asecond network node, the first data packet including payload data andcredit claim data; means for determining at the first network node thatthe credit claim data should be forwarded to a credit accountingauthority; means for transmitting, from the first network node, a seconddata packet to the credit accounting authority, where the second datapacket includes some of the credit claim data; and means fortransmitting, from the first network node, a third data packet to athird network node, where the third data packet includes the payloaddata.